You are in a field that has been divided into squares. Mines have been planted under
99 of those squares. Your task is to clear all of the squares which do not have mines,
leaving the 99 mined squares.

Left-clicking on a square clears it. If you clear a square that actually is mined, the
mine explodes and the game is over. If the square is not mined, the number that appears
in the square is the number of adjacent (horizontally, vertically and diagonally) squares
that are mined. When you start the game a small area of the board is automatically cleared
so that you do not have to begin the game guessing blindly.

Right-clicking (shift, click on a Mac or other computer that does not have a right-click
concept) on a square marks it with a flag to denote that you think the square is mined. The
counter in the upper left corner is the number of mines left to discover, assuming that
all your flags have been planted in squares that actually are mined.